noun the fundamental assumptions from which something is begun or developed or calculated or explained.
— synonyms: basis, base, foundation, groundwork, cornerstone
noun the fleshy part of the human body that you sit on.
— synonyms: buttocks, nates, arse, butt, backside, bum, buns, can
noun lowest support of a structure.
— synonyms: foundation, base, foot, groundwork, substructure, understructure